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1.
Benef Microbes ; 14(1): 1-16, 2023 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-36437811

RESUMO

Probiotics may have potential in reducing cardiovascular disease (CVD) risk in middle-aged persons with borderline metabolic indices. The ability of potential probiotic Lactiplantibacillus plantarum Inducia to reduce CVD risk factors in persons with variable cholesterol and body mass indices (BMI) was assessed. In two parallel-armed double-blind placebo-controlled interventions (n=136) and (n=104), participants daily received either test yoghurt (Inducia) or placebo yoghurt. BMI, blood pressure, plasma glucose, cholesterol, high-sensitivity C-reactive protein (hs-CRP), oxidative stress and immunological markers were measured. Total counts of lactobacilli and L. plantarum Inducia were evaluated using real-time PCR. Significant reduction of total cholesterol, low density lipoprotein cholesterol (LDL-c) and non-high-density cholesterol occurred in both trials. The change in cholesterol (P=0.023) in persons with normal BMI and borderline cholesterol levels after four weeks of yoghurt consumption was detected. A difference was also found between placebo and test yoghurt groups (P=0.042) in LDL-c with normal BMI. Blood glucose reduction (P=0.01) and antioxidative effect was detected in overweight volunteers of the test yoghurt group. The suppression of oxidised LDL was associated with lowered oxidative stress index and total peroxide concentration values and faecal recovery of Inducia. The Inducia strain expresses antioxidative effect on blood lipids and has anti-glycaemic impact that allow to apply it as dietary probiotic supplement for the management of CVD risks in humans.


Assuntos
Doenças Cardiovasculares , Probióticos , Pessoa de Meia-Idade , Humanos , Índice de Massa Corporal , Antioxidantes , LDL-Colesterol , Colesterol , Lactobacillaceae , Doenças Cardiovasculares/prevenção & controle , Método Duplo-Cego
2.
Anaerobe ; 47: 94-103, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28465256

RESUMO

Clostridium difficile infection (CDI) is one of the most prevalent healthcare associated infections in hospitals and nursing homes. Different approaches are used for prevention of CDI. Absence of intestinal lactobacilli and bifidobacteria has been associated with C. difficile colonization in hospitalized patients. Our aim was to test a) the susceptibility of C. difficile strains of different origin and the intestinal probiotic Lactobacillus plantarum Inducia (DSM 21379) to various antimicrobial preparations incl. metronidazole, vancomycin; b) the susceptibility of C. difficile strains to antagonistic effects of the probiotic L. plantarum Inducia, prebiotic xylitol (Xyl) and their combination as a synbiotic (Syn) product; c) the suppression of germination of C. difficile spores in vitro and in vivo in animal model of C. difficile infection with Inducia, Xyl and Syn treatment. The VPI strain 10463 (ATCC 43255), epidemic strain (M 13042) and clinical isolates (n = 12) of C. difficile from Norway and Estonia were susceptible and contrarily L. plantarum Inducia resistant to vancomycin, metronidazole and ciprofloxacin. The intact cells of Inducia, natural and neutralized cell free supernatant inhibited in vitro the growth of tested C. difficile reference strain VPI and Estonian and Norwegian clinical isolates of C. difficile after co-cultivation. This effect against C. difficile sustained in liquid media under ampicillin (0.75 µg/ml) and Xyl (5%) application. Further, incubation of Inducia in the media with 5% Xyl fully stopped germination of spores of C. difficile VPI strain after 48 h. In infection model the 48 hamsters were administered ampicillin (30 mg/kg) and 10-30 spores of C. difficile VPI strain. They also received five days before and after the challenge a pretreatment with a synbiotic (single daily dose of L. plantarum Inducia 1 ml of 1010 CFU/ml and 20% xylitol in 1 ml by orogastric gavage). The survival rate of hamsters was increased to 78% compared to 13% (p = 0.003) survival rate of hamsters who received no treatment. When administered Xyl the survival rate of hamsters reached 56% vs.13% (p = 0.06). In both Syn (6/9, p = 0.003) and Xyl (3/9, p = 0.042) groups the number of animals not colonized with C. difficile significantly increased. In conclusion, the combination of xylitol with L. plantarum Inducia suppresses the germination of spores and outgrowth into vegetative toxin producing cells of C. difficile and reduces the colonization of gut with the pathogen. Putative therapeutical approach includes usage of the synbiotic during antimicrobial therapy for prevention of CDI and its potential to reduce recurrences of CDI.


Assuntos
Clostridioides difficile/fisiologia , Infecções por Clostridium/prevenção & controle , Lactobacillus plantarum/fisiologia , Prebióticos/administração & dosagem , Probióticos/administração & dosagem , Esporos Bacterianos/crescimento & desenvolvimento , Xilitol/administração & dosagem , Animais , Antibacterianos/farmacologia , Antibiose , Clostridioides difficile/efeitos dos fármacos , Clostridioides difficile/isolamento & purificação , Infecções por Clostridium/microbiologia , Modelos Animais de Doenças , Estônia , Humanos , Lactobacillus plantarum/efeitos dos fármacos , Masculino , Mesocricetus , Testes de Sensibilidade Microbiana , Noruega
3.
AJNR Am J Neuroradiol ; 38(4): 801-806, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28126749

RESUMO

BACKGROUND AND PURPOSE: Individuals born from pregnancies complicated by preeclampsia have an elevated risk for cognitive impairment. Deviations in maternal plasma angiokines occur for prolonged intervals before clinical signs of preeclampsia. We hypothesized that fetal brain vascular and nervous tissue development become deviated during maternal progression toward preeclampsia and that such deviations would be detectable by MR imaging. MATERIALS AND METHODS: In this pilot study, 10 matched (gestational and current ages) pairs (5 boys/5 girls, 7-10 years of age) from preeclampsia or control pregnancies were examined by using diffusion tensor MR imaging. An unbiased voxel-based analysis was conducted on fractional anisotropy and mean diffusivity parametric maps. Six brain ROIs were identified for subsequent analysis by tractography (middle occipital gyrus, caudate nucleus and precuneus, cerebellum, superior longitudinal fasciculus, and cingulate gyrus). RESULTS: Statistical differences were present between groups for fractional anisotropy in the caudate nucleus (offspring from preeclamptic gestation > controls), volume of the tract for the superior longitudinal fasciculus (offspring from preeclamptic gestation > controls) and the caudate nucleus (offspring from preeclamptic gestation > controls), and for parallel diffusivity of the cingulate gyrus (offspring from preeclamptic gestation > controls). CONCLUSIONS: These novel preliminary results along with previous results from the same children that identified altered cerebral vessel calibers and increased regional brain volumes justify fully powered MR imaging studies to address the impact of preeclampsia on human fetal brain development.


Assuntos
Imagem de Tensor de Difusão/métodos , Pré-Eclâmpsia/diagnóstico por imagem , Substância Branca/diagnóstico por imagem , Adulto , Anisotropia , Núcleo Caudado/diagnóstico por imagem , Artérias Cerebrais/diagnóstico por imagem , Criança , Feminino , Giro do Cíngulo/diagnóstico por imagem , Humanos , Recém-Nascido , Angiografia por Ressonância Magnética , Masculino , Projetos Piloto , Gravidez
4.
AJNR Am J Neuroradiol ; 37(5): 939-45, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26721772

RESUMO

BACKGROUND AND PURPOSE: Pre-eclampsia is a serious clinical gestational disorder occurring in 3%-5% of all human pregnancies and characterized by endothelial dysfunction and vascular complications. Offspring born of pre-eclamptic pregnancies are reported to exhibit deficits in cognitive function, higher incidence of depression, and increased susceptibility to stroke. However, no brain imaging reports exist on these offspring. We aimed to assess brain structural and vascular anatomy in 7- to 10-year-old offspring of pre-eclamptic pregnancies compared with matched controls. MATERIALS AND METHODS: Offspring of pre-eclamptic pregnancies and matched controls (n = 10 per group) were recruited from an established longitudinal cohort examining the effects of pre-eclampsia. Children underwent MR imaging to identify brain structural and vascular anatomic differences. Maternal plasma samples collected at birth were assayed for angiogenic factors by enzyme-linked immunosorbent assay. RESULTS: Offspring of pre-eclamptic pregnancies exhibited enlarged brain regional volumes of the cerebellum, temporal lobe, brain stem, and right and left amygdalae. These offspring displayed reduced cerebral vessel radii in the occipital and parietal lobes. Enzyme-linked immunosorbent assay analysis revealed underexpression of the placental growth factor among the maternal plasma samples from women who experienced pre-eclampsia. CONCLUSIONS: This study is the first to report brain structural and vascular anatomic alterations in the population of offspring of pre-eclamptic pregnancies. Brain structural alterations shared similarities with those seen in autism. Vascular alterations may have preceded these structural alterations. This pilot study requires further validation with a larger population to provide stronger estimates of brain structural and vascular outcomes among the offspring of pre-eclamptic pregnancies.


Assuntos
Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Pré-Eclâmpsia , Efeitos Tardios da Exposição Pré-Natal/diagnóstico por imagem , Adulto , Criança , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Projetos Piloto , Gravidez , Doenças Vasculares/diagnóstico por imagem , Doenças Vasculares/etiologia
5.
Benef Microbes ; 6(3): 233-43, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25524863

RESUMO

The blood pressure-lowering effect of dairy products holds the potential to decrease the risk of cardiovascular disease (CVD). An open question is if the successful expression of functional properties of the probiotic strain depends on host biomarkers and/or food matrix properties. The probiotic Lactobacillus plantarum strain TENSIA® (DSM 21380) is a novel microorganism with antimicrobial and antihypertensive functional properties. The aim of this study was to characterise the functional properties of the probiotic L. plantarum TENSIA and compare its effects on host anthropometric, clinical, and blood biomarkers when consumed with cheese or yoghurt. This study involved two double-blinded randomised placebo-controlled exploratory trials (ISRCTN15061552 and ISRCTN79645828) of healthy adults over a three-week period. The three-week consumption of probiotic L. plantarum TENSIA in a daily dose of 1×1010 cfu in probiotic cheese or a daily dose of 6×109 cfu in yoghurt with different content of carbohydrates, proteins, and lipids did not significantly change the body mass index (BMI), plasma glucose and lipid levels, or inflammatory markers in the blood. Reduced lowered systolic and diastolic blood pressure values were detected, regardless of food matrix or baseline values for blood pressure and BMI. In conclusion, our study showed that three-week consumption of the probiotic L. plantarum TENSIA either in cheese or yoghurt lowered diastolic and systolic blood pressure regardless of food matrix and baseline values of blood pressure and BMI, confirming the impact of the functional properties of the probiotic strain in decreasing CVD risk.


Assuntos
Anti-Hipertensivos/metabolismo , Doenças Cardiovasculares/microbiologia , Doenças Cardiovasculares/fisiopatologia , Queijo/microbiologia , Lactobacillus plantarum/metabolismo , Probióticos/metabolismo , Iogurte/microbiologia , Adulto , Glicemia/metabolismo , Pressão Sanguínea , Doenças Cardiovasculares/dietoterapia , Doenças Cardiovasculares/metabolismo , Humanos , Lipídeos/sangue , Masculino , Pessoa de Meia-Idade , Adulto Jovem
6.
Placenta ; 35(9): 772-5, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25106880

RESUMO

Effects of placental growth factor (PGF), an angiokine product of fetal trophoblasts and maternal decidual cells, on early decidual angiogenesis are undefined. We used whole-mount immunofluorescence analyses to compare uterus and gestation day 4.5-9.5 mouse implantation sites that differed genetically in fetal or maternal PGF deficiency. Implant site number and embryonic development were similar in Pgf(-/-) and Pgf(+/+) females although Pgf(-/-) lymphatic vessels were anomalous. Correct, fine branching angiogenesis of anti-mesometrial vessels required both conceptus and maternal PGF; correct mesometrial branching angiogenesis depended solely upon conceptus PGF. Thus, PGF is non-redundant for optimizing branching angiogenesis in early decidua.


Assuntos
Implantação do Embrião , Neovascularização Fisiológica , Proteínas da Gravidez/deficiência , Útero/irrigação sanguínea , Animais , Feminino , Masculino , Camundongos , Fator de Crescimento Placentário , Gravidez
7.
Biochim Biophys Acta ; 1837(9): 1490-9, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24560813

RESUMO

In adaption to its specific environmental conditions, the cyanobacterium Acaryochloris marina developed two different types of light-harvesting complexes: chlorophyll-d-containing membrane-intrinsic complexes and phycocyanobilin (PCB) - containing phycobiliprotein (PBP) complexes. The latter complexes are believed to form a rod-shaped structure comprising three homo-hexamers of phycocyanin (PC), one hetero-hexamer of phycocyanin and allophycocyanin (APC) and probably a linker protein connecting the PBPs to the reaction centre. Excitation energy transfer and electron-vibrational coupling in PBPs have been investigated by selectively excited fluorescence spectra. The data reveal a rich spectral substructure with a total of five low-energy electronic states with fluorescence bands at 635nm, 645nm, 654nm, 659nm and a terminal emitter at about 673 nm. The electronic states at ~635 and 645 nm are tentatively attributed to PC and APC, respectively, while an apparent heterogeneity among PC subunits may also play a role. The other fluorescence bands may be associated with three different isoforms of the linker protein. Furthermore, a large number of vibrational features can be identified for each electronic state with intense phonon sidebands peaking at about 31 to 37cm⁻¹, which are among the highest phonon frequencies observed for photosynthetic antenna complexes. The corresponding Huang-Rhys factors S fall in the range between 0.98 (terminal emitter), 1.15 (APC), and 1.42 (PC). Two characteristic vibronic lines at about 1580 and 1634cm⁻¹ appear to reflect CNH⁺ and CC stretching modes of the PCB chromophore, respectively. The exact phonon and vibrational frequencies vary with electronic state implying that the respective PCB chromophores are bound to different protein environments. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy.


Assuntos
Cianobactérias/metabolismo , Ficobiliproteínas/química , Elétrons , Transferência de Energia , Espectrometria de Fluorescência , Vibração
8.
J Dairy Sci ; 95(10): 5495-509, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22863096

RESUMO

Safety of the probiotic Lactobacillus plantarum strain Tensia (DSM 21380) was tested in vitro, in semihard Edam-type cheese, in an animal model and after consumption of the probiotic cheese in double-blind randomized placebo-controlled human intervention studies with different age groups. The susceptibility of L. plantarum Tensia to 8 antibiotics, and the presence of tetracycline (tet M, S, O, K, L) genes and class 1 integron was assessed by applying epsilometer-test and PCR-based methods. Production of biogenic amines by the probiotic strain in decarboxylation medium containing 1% of l-histidine, l-glutamine, l-ornithine, l-arginine, or l-lysine and in cheese was tested by gas chromatography. The biosafety of L. plantarum Tensia was evaluated on National Institutes of Health-line mice fed cheese containing Tensia at a concentration of 9.6 log cfu/g for 30 consecutive days. In human intervention trials in adults and the elderly, the effects of different doses of Edam-type cheese and the probiotic bacterium on BW, gut functionality indices, and host metabolism were evaluated. The strain L. plantarum Tensia was susceptible to all tested antibiotics and did not possess the tetracycline resistance-determining genes tet(L), tet(S) and tet(O), nor did it contain the integron (Int1) gene. However, the strain was tet(K) and tet(M) positive. Lactobacillus plantarum Tensia did not produce potentially harmful biogenic amines, such as histamine or cadaverine. The amount of tyramine produced in the cheese environment during ripening and after 15 wk of storage was below the clinically significant content. In the animal model, no translocation of the administered strain or other microbes into the blood or organs of mice was detected. No harmful effect was observed on body mass index, inflammatory markers, or serum lipidograms during human intervention trials with different age groups at a daily dose of 10.3 or 8.17 log cfu/serving for 3 wk. No negative effect on gastrointestinal welfare was observed, but the consumption of 100g/d for 3 wk caused hard stools from the second week of the trial. The content of total lactobacilli increased in feces, and the presence of the ingested probiotic strain was confirmed after the consumption of cheese. Thus, L. plantarum strain Tensia is suitable for generally recognized as safe (GRAS) and qualified presumption of safety (QPS) criteria because it did not have any undesirable characteristics. The regular semihard Edam-type cheese (fat content of 26%) with the probiotic additive at a daily dose of 50 g or in excess (100g) and with a probiotic daily dose of 10 log cfu for 3 wk was safe.


Assuntos
Queijo/microbiologia , Lactobacillus plantarum/metabolismo , Probióticos/efeitos adversos , Adulto , Fatores Etários , Idoso , Animais , Aminas Biogênicas/efeitos adversos , Aminas Biogênicas/análise , Queijo/efeitos adversos , Queijo/análise , Estudos Cross-Over , Método Duplo-Cego , Fezes/microbiologia , Feminino , Inocuidade dos Alimentos , Genes Bacterianos , Hemólise , Humanos , Masculino , Camundongos , Testes de Sensibilidade Microbiana , Reação em Cadeia da Polimerase , Probióticos/análise
9.
Vopr Pitan ; 81(3): 74-81, 2012.
Artigo em Russo | MEDLINE | ID: mdl-22888676

RESUMO

The probiotic L. plantarum strain TENSIA (DSM 21380) is a novel microorganism having antimicrobial and antihypertensive properties. The aim of the study was to test the efficacy of the consumption of the cheese, comprising the novel strain TENSIA on multiple health markers of humans. Human intervention trial showed that the blood pressure lowering effect of cheese, comprising L. plantarum TENSIA was evident in healthy volunteers with high normal blood pressure up to normal values. The 3-week consumption of the prohiotic cheese did not increase the CVD risk factors like BMI, the level of plasma lipids and glucose as well as inflammatory and immunological markers of human body.


Assuntos
Pressão Sanguínea/efeitos dos fármacos , Queijo/microbiologia , Lactobacillus plantarum/crescimento & desenvolvimento , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipídeos/sangue , Probióticos/farmacologia , Adolescente , Adulto , Idoso , Índice de Massa Corporal , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Adulto Jovem
10.
J Phys Chem B ; 115(14): 4042-52, 2011 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-21417350

RESUMO

Difference fluorescence line-narrowing spectroscopy at 4.5 K was employed to investigate electron-phonon and electron-vibrational coupling strengths of the lower exciton level of water-soluble chlorophyll-binding protein (WSCP) from cauliflower reconstituted with chlorophyll a or chlorophyll b, respectively. The electron-phonon coupling is found to be moderate with integral Huang-Rhys factors S in the order of 0.81-0.85. A weak dependence of S on excitation wavelength within the inhomogeneously broadened fluorescence origin band is attributed to a sizable contribution of nonresonant excitation that varies with excitation wavelength. The strongly asymmetric and highly structured one-phonon profile is characterized by a peak phonon frequency (ω(m)) of ~24 cm(-1) and further discernible peaks at 48 and 88 cm(-1), respectively. A structural assignment of this unusual one-phonon profile is proposed. As will be shown in the accompanying paper (part II) (DOI 10.1021/jp111457t), the parameters of electron-phonon coupling readily account for shape and position of the fluorescence origin bands at 666.1 and 683.8 nm for chlorophyll b- and chlorophyll a-WSCP, respectively. A rich structure of S(1)→S(0) vibrational frequencies was resolved in the wavenumber range between 180 and 1665 cm(-1) for both chlorophyll a- and chlorophyll b-WSCP. The corresponding individual Huang-Rhys factors fall in the range between 0.0011 and 0.0500. To the best of our knowledge, this is the first report of S-factors for vibrational modes of chlorophyll b. Most remarkable is the presence of two additional modes at 228 and 327 cm(-1) compared with the vibrational spectrum of chlorophyll in solution. The additional modes can most likely be attributed to H-bond formation in the vicinity of the chlorophyll molecule bound by WSCP.


Assuntos
Clorofila/química , Complexos de Proteínas Captadores de Luz/química , Brassica/metabolismo , Clorofila A , Elétrons , Complexos de Proteínas Captadores de Luz/genética , Complexos de Proteínas Captadores de Luz/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Espectrometria de Fluorescência , Termodinâmica , Água/química
11.
J Phys Chem B ; 115(14): 4053-65, 2011 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-21417356

RESUMO

Persistent spectral hole burning at 4.5 K has been used to investigate the excitonic energy level structure and the excited state dynamics of the recombinant class-IIa water-soluble chlorophyll-binding protein (WSCP) from cauliflower. The hole-burned spectra are composed of four main features: (i) a narrow zero-phonon hole (ZPH) at the burn wavelength, (ii) a number of vibrational ZPHs, (iii) a broad low-energy hole at ~665 and ~683 nm for chlorophyll b- and chlorophyll a-WSCP, respectively, and (iv) a second satellite hole at ~658 and ~673 nm for chlorophyll b- and chlorophyll a-WSCP, respectively. The doublet of broad satellite holes is assigned to an excitonically coupled chlorophyll dimer. The lower-energy holes at ~665 and ~683 nm for chlorophyll b- and chlorophyll a-WSCP, respectively, represent the lower exciton states. Taking into account the parameters of electron-phonon coupling, the lower exciton state can be assigned as the fluorescence origin. The lower exciton state is populated by two processes: (i) exciton relaxation from the higher exciton state and (ii) vibrational relaxation within the lower exciton state. Assuming identical site energies for the two excitonically coupled chlorophyll molecules, the dipole-dipole interaction energy J is directly determined to be 85 and 100 cm(-1) for chlorophyll b- and chlorophyll a-WSCP, respectively, based on the positions of the satellite holes. The Gaussian low-energy absorption band identified by constant fluence hole burning at 4.5 K has a width of ~150 cm(-1) and peaks at 664.9 and 682.7 nm for chlorophyll b- and chlorophyll a-WSCP, respectively. The action spectrum is broader and blue-shifted compared to the fluorescent lower exciton state. This finding can be explained by a slow protein relaxation between energetically inequivalent conformational substates within the lowest exciton state in agreement with the results of Schmitt et al. (J. Phys. Chem. B2008, 112, 13951).


Assuntos
Clorofila/química , Complexos de Proteínas Captadores de Luz/química , Brassica/metabolismo , Clorofila A , Elétrons , Complexos de Proteínas Captadores de Luz/genética , Complexos de Proteínas Captadores de Luz/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Espectrometria de Fluorescência , Termodinâmica , Vibração , Água/química
12.
Biophys J ; 79(3): 1561-72, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10969017

RESUMO

Results from high-pressure and Stark hole-burning experiments on isolated chlorosomes from the green sulfur bacterium Chlorobium tepidum are presented, as well as Stark hole-burning data for bacteriochlorophyll c (BChl c) monomers in a poly(vinyl butyral) copolymer film. Large linear pressure shift rates of -0.44 and -0.54 cm(-1)/MPa were observed for the chlorosome BChl c Q(y)-band at 100 K and the lowest Q(y)-exciton level at 12 K, respectively. It is argued that approximately half of the latter shift rate is due to electron exchange coupling between BChl c molecules. The similarity between the above shift rates and those observed for the B875 and B850 BChl a rings of the light-harvesting complexes of purple bacteria is emphasized. For BChl c monomer, fDeltamu++ = 0.35 D, where Deltamu+ is the dipole moment change for the Q(y) transition and f is the local field correction factor. The data establish that Deltamu+ is dominated by the matrix-induced contribution. The change in polarizability (Deltaalpha) for the Q(y) transition of the BChl c monomer is estimated at 19 A(3), which is essentially identical to that of the Chl a monomer. Interestingly, no Stark effects were observed for the lowest exciton level of the chlorosomes (maximum Stark field of 10(5) V/cm). Possible explanations for this are given, and these include consideration of structural models for the chlorosome BChl c aggregates.


Assuntos
Bacterioclorofilas , Chlorobi/fisiologia , Organelas/fisiologia , Complexo de Proteínas do Centro de Reação Fotossintética/química , Proteínas de Bactérias/química , Complexos de Proteínas Captadores de Luz , Complexo de Proteínas do Centro de Reação Fotossintética/metabolismo , Polivinil , Pressão , Espectrofotometria
13.
Photochem Photobiol ; 71(5): 574-81, 2000 May.
Artigo em Inglês | MEDLINE | ID: mdl-10818788

RESUMO

Low-temperature absorption, fluorescence and persistent non-photochemical hole-burned spectra are reported for the CP29 chlorophyll (Chl) a/b antenna complex of photosystem II of green plants. The absorption-origin band of the lowest Qy-state lies at 678.2 nm and carries a width of approximately 130 cm-1 that is dominated by inhomogeneous broadening at low temperatures. Its absorption intensity is equivalent to that of one of the six Chl a molecules of CP29. The absence of a significant satellite hole structure produced by hole burning, within the absorption band of the lowest state, indicates that the associated Chl a molecule is weakly coupled to the other Chl and, therefore, that the lowest-energy state is highly localized on a single Chl a molecule. The electron-phonon coupling of the 678.2 nm state is weak with a Huang-Rhys factor S of 0.5 and a peak phonon frequency (omega m) of approximately 20 cm-1. These values give a Stokes shift (2S omega m) in good agreement with the measured positions of the absorption band at 678.2 nm and a fluorescence-origin band at 679.1 nm. Zero-phonon holes associated with the lowest state have a width of approximately 0.05 cm-1 at 4.2 K, corresponding to a total effective dephasing time of approximately 400 ps. The temperature dependence of the zero-phonon holewidth indicates that this time constant is dominated at temperatures below 8 K by pure dephasing/spectral diffusion due to coupling of the optical transition to the glass-like two-level systems of the protein. Zero-phonon hole-widths obtained for the Chl b bands at 638.5 and 650.0 nm, at 4.2 K, lead to lower limits of 900 +/- 150 fs and 4.2 +/- 0.3 ps, respectively, for the Chl b-->Chl a energy-transfer times. Downward energy transfer from the Chl a state(s) at 665.0 nm occurs in 5.3 +/- 0.6 ps at 4.2 K.


Assuntos
Complexo de Proteínas do Centro de Reação Fotossintética/química , Spinacia oleracea/química , Complexos de Proteínas Captadores de Luz , Complexo de Proteína do Fotossistema II
14.
Opt Lett ; 22(5): 310-2, 1997 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-18183185

RESUMO

We report experiments on ultrashort pulses that maintain their strong lateral and longitudinal localization in a bulk linear highly dispersive medium. The diameter of the central peak and the temporal width of the field autocorrelation function of the pulses were 20mum and 210 fs, respectively, and the spatiotemporal structure was preserved in the course of 7-cm propagation in the sample. The pulses were obtained with a computer hologram designed for generating the Bessel beam and can be applied in femtosecond laser optics.

15.
Opt Lett ; 21(1): 83-5, 1996 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-19865312

RESUMO

Spectral phase codes are used as storage addresses in a frequency-selective optical memory. Data are engraved over a 1.5-THz-wide spectral interval. With the help of a ferroelectric liquid-crystal modulator it takes less than 100 micros to retrieve any spectrally addressed data.

16.
Opt Lett ; 21(16): 1292-4, 1996 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-19876329

RESUMO

The spatial routing of a temporally encoded stream of optical pulses is experimentally demonstrated. The holograms that link the temporally shaped addresses to the def lection directions are engraved in a photorefractive crystal.

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